As semiconductor products are miniaturized and highly integrated, researches on patterning technology have been made to form patterns for improving new functions of the devices.
Specifically, microelectronic circuit, digital storage unit, display, and sensor having nano devices of 100 nm or less can obtain excellent characteristics using a very small amount of nano material. Therefore, in various industry fields, nano material is considered as new material that can meet the demands of high-tech industry fields. In the development of such nano devices, one of the most important technologies is the nano patterning technology.
The patterning technology with high integration has been developed as the core technology in fabricating semiconductor devices. Generally, the patterning technology using optics or beam includes a photo lithography, an electron-beam lithography, an X-ray lithography, and so on. Such a lithography process uses photoresist sensitive to the irradiation of light and forms patterns using an etching technique. Accordingly, a conventional lithography technology is time-consuming, cost-consuming and complicated in terms of the apparatus and process.
Also, polymer materials used as the photoresist have reached physical limitation and are difficult to apply to a curved surface.
In recent years, soft-lithography technique has been proposed as a new concept of patterning technology, which is different from the typical optical lithography technology.
The soft-lithography technique includes a microcontact printing (μ CP) and a nano-imprinting lithography. The soft-lithography technique is to fabricate patterns or structures using a flexible polymer stamp to which organic material is applied, without using light or high-energy particles.
According to the microcontact printing (μ CP) using a self-assembled material, ink (self-assembled monolayer (SAM)) is applied to a PolyDiMethylSiloxane (PDMS) elastomer stamp with micron patterns, and patterns are transferred onto a surface of a substrate after contact of the stamp with the surface. In this manner, desired thin film patterns can be locally formed on a plane.
Also, when forming conductive patterns of semiconductor devices or display devices, a stamp is formed by coating a desired metal on a polymer material, such as PDMS, having convex portions (), and the stamp is placed on a conductive substrate. Then, an external voltage is applied to form a charged zone with charges on the substrate contacting the convex portions of the metal-coated stamp. Particles or molecules charged with opposite charges to those of the charged zone are coated on the charged zone, and the self-assembled monolayer (SAM) is locally patterned on the plane, thereby directly forming the desired thin film patterns.
However, the stamp formed by coating the metal on the flexible PDMS material is rigid due to the presence of the metal. Therefore, when the charged zone is formed by contacting the stamp with the large-sized substrate so as to form the conductive patterns, it is impossible to properly contact the substrate with the stamp.
Since such a charged zone is not properly matched with the desired pattern region, it is difficult to properly form the conductive patterns in the large-sized substrate. Further, patterns may be opened at each step of the subsequent processes.